Solid-state imaging device, method of manufacturing the same, and electronic device

ABSTRACT

The present disclosure relates to a solid-state imaging device capable of further decreasing reflectivity, a method of manufacturing the same, and an electronic device. The solid-state imaging device includes a semiconductor substrate on which a photoelectric converting unit is formed for each of a plurality of pixels, and an antireflection structure provided on a light incident surface side from which light is incident on the semiconductor substrate in which a plurality of types of projections of different heights is formed. The antireflection structure is formed by performing processing of digging a light incident surface of the semiconductor substrate in a plurality of stages with different processing conditions. The antireflection structure is the structure in which a second projection lower than a first projection is formed between the first projections of predetermined height. The present technology may be applied to a CMOS image sensor, for example.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/410,509, filed May 13, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/309,521, filed Nov. 8, 2016, now U.S. Pat. No.10,325,950, which is a national stage application under 35 U.S.C. 371and claims the benefit of PCT Application No. PCT/JP2015/063058 havingan international filing date of May 1, 2015, which designated the UnitedStates, which PCT application claimed the benefit of Japanese PatentApplication No. 2014-102315 filed May 16, 2014, the disclosures of whichare incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a solid-state imaging device, a methodof manufacturing the same, and an electronic device, and especiallyrelates to the solid-state imaging device capable of further decreasingreflectivity, the method of manufacturing the same, and the electronicdevice.

BACKGROUND ART

Conventionally, a solid-state image sensor such as a charge coupleddevice (CCD)/complementary metal oxide semiconductor (CMOS) image sensoris used, for example, in an electronic device having an imaging functionsuch as a digital still camera and a digital video camera.

For example, incident light incident on the CMOS image sensor issubjected to photoelectric conversion by a photodiode (PD) being aphotoelectric converting unit included in a pixel. Then, an electriccharge generated by the PD is transferred to floating diffusion (FD)through a transfer transistor and an amplification transistor outputs apixel signal of a level according to the electric charge accumulated inthe FD.

In a conventional solid-state image sensor, there is a case in which thelight incident on the solid-state image sensor is reflected therein andflare and ghost occur by the reflected light imaged in an image. Forexample, the light reflected by an on-chip lens and a silicon surface ofthe pixel of each color is reflected by a seal glass surface and aninfrared radiation cutoff filter surface to be incident again on thephotoelectric converting unit and the flare occurs. Also, for example,red light reflected by the silicon surface of the red pixel and theon-chip lens surface is reflected by a multicoated surface of theinfrared radiation cutoff filter to be incident again on thephotoelectric converting unit and the ghost which looks like a red balloccurs.

In order to prevent such reflection of the light on the silicon surfaceto decrease the occurrence of the flare and ghost, a structure in whicha fine uneven structure is periodically arranged, a so-called moth-eyestructure is known. In the moth-eye structure, a refractive indexgradually changes, so that reflectivity may be decreased.

For example, Patent Document 1 suggests the so-called moth-eye structurein which the fine uneven structure is formed on an interface on a sideof a light receiving surface of a silicon layer in which the photodiodeis formed as the structure of preventing the reflection of the incidentlight.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent Application Laid-Open No. 2013-33864

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

When the above-described moth-eye structure is processed by dry etching,a deeper concave portion may be formed by setting long processing time.However, when the moth-eye structure in which the concave portion isdeep is formed by such processing, it is worried that processing damageincreases, for example, a dark characteristic is deteriorated.Furthermore, it is worried that a trouble such as a residue occurs in apost process due to increased unevenness by the moth-eye structure.Therefore, it is required to avoid such worry to further decrease thereflectivity.

The present disclosure is achieved in view of such a condition and anobject thereof is to further decrease the reflectivity.

Solutions to Problems

A solid-state imaging device according to one aspect of the presentdisclosure is provided with a semiconductor substrate on which aphotoelectric converting unit is formed for each of a plurality ofpixels, and an antireflection structure being the structure provided ona light incident surface side from which light is incident on thesemiconductor substrate in which a plurality of types of projections ofdifferent heights is formed.

A method of manufacturing a solid-state imaging device according to oneaspect of the present disclosure includes a step of forming anantireflection structure being the structure provided on a lightincident surface side from which light is incident on a semiconductorsubstrate on which a photoelectric converting unit is formed for each ofa plurality of pixels in which a plurality of types of projections ofdifferent heights is formed by performing processing of digging a lightincident surface of the semiconductor substrate in a plurality of stageswith different processing conditions.

An electronic device according to one aspect of the present disclosureis provided with a solid-state imaging device provided with asemiconductor substrate on which a photoelectric converting unit isformed for each of a plurality of pixels, and an antireflectionstructure being the structure provided on a light incident surface sidefrom which light is incident on the semiconductor substrate in which aplurality of types of projections of different heights is formed.

In one aspect of the present disclosure, an antireflection structurebeing the structure in which a plurality of types of projections ofdifferent heights is formed is provided on a light incident surface sidefrom which light is incident on a semiconductor substrate on which aphotoelectric converting unit is formed for each of a plurality ofpixels. In addition, the antireflection structure is formed byperforming processing of digging a light incident surface of thesemiconductor substrate in a plurality of stages with differentprocessing conditions.

Effects of the Invention

According to one aspect of the present disclosure, the reflectivity maybe further decreased.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a schematic configuration of a solid-stateimaging device according to the present disclosure.

FIG. 2 is a view illustrating a cross-sectional configuration example ofa pixel according to a first embodiment.

FIG. 3 is a view illustrating an antireflection structure.

FIG. 4 is a view illustrating a conventional antireflection structure.

FIG. 5 is a view illustrating reflectivity on a light incident surface.

FIG. 6 is a view illustrating a method of manufacturing the solid-stateimaging device.

FIG. 7 is a view illustrating the method of manufacturing thesolid-state imaging device.

FIG. 8 is a view illustrating a variation of the antireflectionstructure.

FIG. 9 is a block diagram illustrating a configuration example of theimaging device as an electronic device according to the presentdisclosure.

MODE FOR CARRYING OUT THE INVENTION

A mode for carrying out the present disclosure (hereinafter, referred toas an embodiment) is hereinafter described. Meanwhile, the descriptionis given in the following order.

1. Schematic Configuration Example of Solid-State Imaging Device

2. Pixel Structure according to This Embodiment

3. Example of Application to Electronic Device

Hereinafter, a specific embodiment to which the present technology isapplied is described in detail with reference to the drawings.

1. Schematic Configuration Example of Solid-State Imaging Device

FIG. 1 illustrates a schematic configuration of a solid-state imagingdevice according to the present disclosure.

A solid-state imaging device 1 in FIG. 1 is configured such that asemiconductor substrate 12 formed of silicon (Si), for example, as asemiconductor includes a pixel array unit 3 in which pixels 2 arearranged in a two-dimensional array pattern and a peripheral circuitunit around the same. The peripheral circuit unit includes a verticaldriving circuit 4, a column signal processing circuit 5, a horizontaldriving circuit 6, an output circuit 7, a control circuit 8 and thelike.

The pixel 2 includes a photodiode as a photoelectric conversion elementand a plurality of pixel transistors. A plurality of pixel transistorsis formed of four MOS transistors which are a transfer transistor, aselection transistor, a reset transistor, and an amplificationtransistor, for example.

The pixel 2 may also have a shared pixel structure. The pixel sharedstructure is formed of a plurality of photodiodes, a plurality oftransfer transistors, one shared floating diffusion (floating diffusionregion), and other shared pixel transistors one for each type. That isto say, the shared pixel is configured such that the photodiodes and thetransfer transistors formed of a plurality of unit pixels share otherpixel transistors one for each type.

The control circuit 8 receives an input clock and data giving a commandof an operation mode and the like and outputs data of internalinformation and the like of the solid-state imaging device 1. That is tosay, the control circuit 8 generates a clock signal and a control signalserving as a reference of operation of the vertical driving circuit 4,the column signal processing circuit 5, and the horizontal drivingcircuit 6 on the basis of a vertical synchronization signal, ahorizontal synchronization signal, and a master clock. Then, the controlcircuit 8 outputs the generated clock signal and control signal to thevertical driving circuit 4, the column signal processing circuit 5, thehorizontal driving circuit 6 and the like.

The vertical driving circuit 4 formed of a shift register, for example,selects pixel driving wiring 10, supplies a pulse for driving the pixel2 to the selected pixel driving wiring 10, and drives the pixels 2 in arow unit. That is to say, the vertical driving circuit 4 sequentiallyselects to scan the pixels 2 in the pixel array unit 3 in a row unit ina vertical direction and supplies a pixel signal based on a signalcharge generated according to a light receiving amount by aphotoelectric converting unit of each pixel 2 to the column signalprocessing circuit 5 through a vertical signal line 9.

The column signal processing circuit 5 arranged for each column of thepixels 2 performs signal processing such as noise removal on the signalsoutput from the pixels 2 of one column for each pixel column. Forexample, the column signal processing circuit 5 performs the signalprocessing such as correlated double sampling (CDS) for removing a fixedpattern noise peculiar to the pixel and AD conversion.

The horizontal driving circuit 6 formed of a shift register, forexample, sequentially selects each of the column signal processingcircuits 5 by sequentially outputting horizontal scanning pulses andoutputs the pixel signal from each of the column signal processingcircuits 5 to a horizontal signal line 11.

The output circuit 7 performs signal processing on the signalssequentially supplied from each of the column signal processing circuits5 through the horizontal signal line 11 to output. There is a case inwhich the output circuit 7 merely buffers, for example, or a case inwhich this performs block level adjustment, column variation correction,and various types of digital signal processing. An input/output terminal13 communicates signals with the outside.

The solid-state imaging device 1 formed in the above-described manner isa CMOS image sensor referred to as a column AD type in which the columnsignal processing circuit 5 which performs CDS processing and ADconversion processing is arranged for each pixel column.

The solid-state imaging device 1 also is a rear surface irradiation MOSsolid-state imaging device on which light is incident from a rearsurface side on a side opposite to a surface of the semiconductorsubstrate 12 on which the pixel transistor is formed.

2. Pixel Structure According to this Embodiment

FIG. 2 is a view illustrating a cross-sectional configuration example ofthe pixel 2 according to this embodiment.

As illustrated in FIG. 2 , the solid-state imaging device 1 is formed ofthe semiconductor substrate 21, an antireflection film 22, a flatteningfilm 23, a color filter layer 24, and an on-chip lens layer 25 stackedon each other; FIG. 2 illustrates a cross-section of three pixels 2-1 to2-3.

The semiconductor substrate 21 is a silicon wafer obtained by thinlyslicing a single crystal of high purity silicon, for example, on whichphotoelectric converting units 31-1 to 31-3 each of which converts theincident light to an electric charge by the photoelectric conversion toaccumulate are formed for the pixels 2-1 to 2-3, respectively.

The antireflection film 22 has a stacked structure obtained by stackinga fixed charge film and an oxidized film, for example; a high-kinsulating thin film obtained by an atomic layer deposition (ALD) methodmay be used, for example. Specifically, hafnium oxide (HfO₂), aluminumoxide (Al₂O₃), titanium oxide (TiO₂), strontium titan oxide (STO) andthe like may be used. In the example in FIG. 2 , the antireflection film22 is formed of a hafnium oxide film 32, an aluminum oxide film 33, anda silicon oxide film 34 stacked on each other.

In addition, a light-shielding film 35 is formed in a region serving asa boundary between the pixels 2 on the antireflection film 22. Amaterial which shields light may be used as a material of thelight-shielding film 35; a single layered metal film of titanium (Ti),titanium nitride (TiN), tungsten (W), aluminum (Al), tungsten nitride(WN) or the like is used, for example. Alternatively, a stacked film ofsuch metal (for example, a stacked film of titanium and tungsten and astacked film of titanium nitride and tungsten) may also be used as thelight-shielding film 35.

The flattening film 23 formed by depositing an insulating material whichtransmits light, for example, flattens a surface. An organic materialsuch as resin may be used, for example, as the material of theflattening film 23.

The color filter layer 24 is formed of filters 36 each of whichtransmits light of a predetermined color arranged for each pixel 2; thefilters 36 which transmit the light of three primary colors (red, green,and blue) are arranged in a so-called Bayer array, for example. Forexample, as illustrated, a filter 36-1 which transmits red (R) light isarranged for the pixel 2-1, a filter 36-2 which transmits green (G)light is arranged for the pixel 2-2, and a filter 36-3 which transmitsblue (B) light is arranged for the pixel 2-3. The color filter layer 24is formed by spin coating of photosensitive resin containing pigmentssuch as colorant and dye, for example.

The on-chip lens layer 25 is formed of on-chip lenses 37 each of whichcondenses light on the photoelectric converting unit 31 arranged foreach pixel 2; as illustrated, on-chip lenses 37-1 to 37-3 are arrangedfor the pixels 2-1 to 2-3, respectively. The on-chip lens 37 is formedof a resin material such as styrene resin, acrylic resin,styrene-acrylic copolymer resin, or siloxane resin, for example.

The solid-state imaging device 1 is formed in this manner, and the lightincident on the solid-state imaging device 1 from an upper side of FIG.2 is condensed by the on-chip lenses 37 for the respective pixels 2 tobe spectrally dispersed to respective colors by the filters 36. Then,the light transmitted through the flattening film 23 and theantireflection film 22 to be incident on the semiconductor substrate 21is subjected to the photoelectric conversion by the photoelectricconverting unit 31 for each pixel 2.

Hereinafter, a surface on a side from which the light is incident on thesolid-state imaging device 1 (upper surface in FIG. 2 ) is appropriatelyreferred to as a light incident surface. An antireflection structure 41formed of a fine uneven structure (a so-called moth-eye structure) onthe light incident surface of the semiconductor substrate 21 is providedon the light incident surface of the semiconductor substrate 21 forinhibiting reflection of the incident light incident on thesemiconductor substrate 21. For example, in the configuration exampleillustrated in FIG. 2 , antireflection structures 41-1 to 41-3 areprovided for the pixels 2-1 to 2-3, respectively, and a flat surface isprovided in an inter-pixel region between the pixels 2-1 to 2-3.

Next, the antireflection structure 41 is described with reference toFIG. 3 .

FIG. 3 illustrates the antireflection structure 41 formed on the lightincident surface of the semiconductor substrate 21 in an enlargedmanner. A plan view of the antireflection structure 41 is illustrated ona lower side of FIG. 3 and a cross-sectional view taken along A-A′ inthe plan view is illustrated on an upper side of FIG. 3 .

The antireflection structure 41 provided on the light incident surfaceof the semiconductor substrate 21 is configured such that a refractiveindex gradually changes by a structure in which a plurality of types ofprojections of different heights is formed. In an example in FIG. 3 , itis configured such that the refractive index changes in two stages byproviding two types of projections 42 and 43 of different heights.Specifically, the antireflection structure 41 is configured such that aplurality of projections 42 of 250 nm in height is formed at a 200nm-pitch and the projection 43 of 125 nm in height is formed between theprojections 42.

For example, as illustrated in FIG. 4 , a conventional antireflectionstructure 41′ is formed only of the projections 42 of the same heightand a flat surface is formed between the projections 42. On the otherhand, the antireflection structure 41 in FIG. 3 has the structure inwhich the projection 43 is formed in a flat site between the projections42 at the time of processing with a processing condition of forming onlythe projections 42 as with the conventional antireflection structure41′.

By configuring the antireflection structure 41 in this manner, therefractive index changes in two stages on the light incident surface, sothat reflectivity on the light incident surface of the semiconductorsubstrate 21 may be decreased from that in the conventionalantireflection structure 41′.

For example, the reflectivity on the light incident surface is describedwith reference to FIG. 5 .

In FIG. 5 , a wavelength of the light incident on the light incidentsurface and the reflectivity on the light incident surface are plottedalong the abscissa and the ordinate, respectively.

A solid line in FIG. 5 indicates the reflectivity on the light incidentsurface having a flat structure without the moth-eye structure formed.Also, a broken line in FIG. 5 indicates the reflectivity on the lightincident surface on which the conventional antireflection structure 41′formed only of the projections 42 of the same height is provided asillustrated in FIG. 4 . Also, a dashed line in FIG. 5 indicates thereflectivity on the light incident surface on which the antireflectionstructure 41 of this embodiment as illustrated in FIG. 3 , that is tosay, the antireflection structure 41 formed of the two types ofprojections 42 and 43 of the different heights is provided.

As illustrated in FIG. 5 , with the antireflection structure 41, it ispossible to significantly decrease the reflectivity at all thewavelengths from that with the conventional antireflection structure41′. Meanwhile, although it is illustrated that the reflectivity isdecreased also with the conventional antireflection structure 41′ ascompared to that on the light incident surface having the flatstructure, the reflectivity is not less than 5% across all thewavelengths of the incident light. In contrast, it is illustrated thatthe reflectivity may be inhibited to 1% or less in the vicinity of anarea from 550 nm to 600 nm of the wavelength of the incident light, forexample, with the antireflection structure 41.

Therefore, it is possible to inhibit the reflection of the incidentlight incident on the semiconductor substrate 21 by the antireflectionstructure 41 capable of decreasing the reflectivity in this manner, sothat it is possible to improve sensitivity of the pixel 2 to improvequality of the image taken by the solid-state imaging device 1.

The solid-state imaging device 1 is configured in this manner, and theantireflection structure 41 formed of a plurality of types ofprojections of the different heights may be manufactured by performingprocessing of digging the light incident surface of the semiconductorsubstrate 21 in a plurality of stages with different processingconditions.

Next, a method of manufacturing the solid-state imaging device 1 isdescribed with reference to FIGS. 6 and 7 .

First, as illustrated in an uppermost stage of FIG. 6 , at a first step,a hard mask layer 51 formed of silicon oxide (SiO₂) and the like isdeposited on a rear surface of the semiconductor substrate 21 thinnedfrom the rear surface side after the photoelectric converting unit 31 isformed and resist 52 is applied thereon.

At a second step, a pattern corresponding to a region in which theprojection 42 is formed is exposed and the resist 52 in a portion otherthan the region is removed as illustrated in a second stage from aboveof FIG. 6 . According to this, the resist 52 has a shape in which thepattern corresponding to the region in which the projection 42 is formedis left.

At a third step, dry etching is performed with a predetermined ionamount set in a first processing condition, then the hard mask layer 51is removed according to the pattern of the resist 52 and the rearsurface of the semiconductor substrate 21 is processed. According tothis, the rear surface of the semiconductor substrate 21 is dug and aconcave portion having a V cross-sectional shape is formed according toa crystal structure of the semiconductor substrate 21 as illustrated ina third stage from above of FIG. 6 .

At a fourth step, the dry etching is performed with a second processingcondition different from the first processing condition, for example,the second processing condition set to increase the ion amount than thatin the first processing condition. In this manner, the fine unevenstructure formed of the two types of projections 42 and 43 of thedifferent heights is formed as illustrated in a fourth stage from aboveof FIG. 6 by performing etching in two steps with the differentprocessing conditions.

Next, as illustrated in an uppermost stage in FIG. 7 , at a fifth step,the hard mask layer 51 and the resist 52 are removed.

At a sixth step, as illustrated in a second stage from above of FIG. 7 ,the hafnium oxide film 32, the aluminum oxide film 33, and the siliconoxide film 34 are stacked on an entire surface including the fine unevenstructure formed on the rear surface of the semiconductor substrate 21,so that the antireflection film 22 is deposited.

At a seventh step, as illustrated in a third stage from above of FIG. 7, the light-shielding film 35 is formed in the region serving as theboundary between the pixels 2 on the antireflection film 22.

Then, at an eighth step, as illustrated in a fourth stage from above ofFIG. 7 , the flattening film 23 is deposited and the color filter layer24 and the on-chip lens layer 25 are stacked, and the solid-stateimaging device 1 is manufactured.

As described above, in the solid-state imaging device 1, it is possibleto provide the antireflection structure 41 in which the two types ofprojections 42 and 43 of the different heights are formed by etching intwo steps with different processing conditions.

At that time, in the solid-state imaging device 1, it is possible toprevent occurrence of a trouble (for example, deterioration in a darkcharacteristic and a residue) worried when long processing time is set,for example, described above. That is to say, the solid-state imagingdevice 1 may have a more excellent characteristic as compared to aconfiguration in which the concave portion of the fine uneven structureis formed deeply. That is to say, the solid-state imaging device 1 maydecrease the reflectivity without forming the deep concave portion ofthe fine uneven structure.

According to this, the solid-state imaging device 1 may preventoccurrence of flare or ghost described above, for example, and may takea higher quality image.

Although the antireflection structure 41 is formed of the two types ofprojections 42 and 43 of the different heights in the above-describedembodiment, this may also be formed of two or more types of projectionsof different heights. For example, it is possible to form theantireflection structure 41 of three or more types of projections ofdifferent heights.

FIG. 8 illustrates a variation of the antireflection structure.

An antireflection structure 41A illustrated in FIG. 8 is configured suchthat three types of projections 42, 43, and 44 of different heights areformed on the light incident surface of the semiconductor substrate 21.That is to say, the antireflection structure 41A is configured such thatthe projection 44 of medium height is formed between the high projection42 and the low projection 43.

By providing the three types of projections 42, 43, and 44 of thedifferent heights in this manner, the antireflection structure 41A isconfigured such that the refractive index changes in three stages andthe reflectivity may be further decreased.

Meanwhile, although the configuration in which the antireflectionstructure 41 is provided on the light incident surface of thesemiconductor substrate 21 is described in this embodiment, theantireflection structure 41 may also be provided in a place other thanthe light incident surface as long as this is provided on a side fromwhich the light is incident on the semiconductor substrate 21. Forexample, it is possible to provide the antireflection structure in whicha plurality of projections of the different heights is formed on asurface of the flattening film 23 on a light incident surface side ofthe semiconductor substrate 21, a surface of the color filter layer 24,and a surface of the on-chip lens layer 25.

3. Example of Application to Electronic Device

Application of the technology of the present disclosure is not limitedto that to the solid-state imaging device. That is to say, thetechnology of the present disclosure may be generally applied toelectronic devices in which the solid-state imaging device is used in animage capturing unit (photoelectric converting unit) such as an imagingdevice such as a digital still camera and a video camera, a portableterminal device having an imaging function, and a copying machine inwhich the solid-state imaging device is used in the image reading unit.The solid-state imaging device may have a form formed as one chip or mayhave a modular form having the imaging function in which an imaging unitand a signal processor or an optical system are collectively packaged.

FIG. 9 is a block diagram illustrating a configuration example of theimaging device as the electronic device according to the presentdisclosure.

An imaging device 200 in FIG. 9 is provided with an optical unit 201formed of a lens group and the like, a solid-state imaging device(imaging device) 202 to which the configuration of the solid-stateimaging device 1 in FIG. 1 is adopted, and a digital signal processor(DSP) circuit 203 being a camera signal processing circuit. The imagingdevice 200 is also provided with a frame memory 204, a display unit 205,a recording unit 206, an operating unit 207, and a power supply unit208. The DSP circuit 203, the frame memory 204, the display unit 205,the recording unit 206, the operating unit 207, and the power supplyunit 208 are connected to one another through a bus line 209.

The optical unit 201 captures incident light (image light) from anobject to form an image on an imaging surface of the solid-state imagingdevice 202. The solid-state imaging device 202 converts a light amountof the incident light the image of which is formed on the imagingsurface thereof by the optical unit 201 to an electric signal in a pixelunit to output as a pixel signal. As the solid-state imaging device 202,the solid-state imaging device 1 in FIG. 1 , that is to say, thesolid-state imaging device in which the reflectivity on the lightincident surface is inhibited may be used.

The display unit 205 formed of a panel display device such as a liquidcrystal panel and an organic electro luminescence (EL) panel, forexample, displays a moving image or a still image taken by thesolid-state imaging device 202. The recording unit 206 records themoving image or the still image taken by the solid-state imaging device202 in a recording medium such as a hard disk and a semiconductormemory.

The operating unit 207 issues an operation command regarding variousfunctions of the imaging device 200 under operation by a user. The powersupply unit 208 appropriately supplies various power sources serving asoperation power sources of the DSP circuit 203, the frame memory 204,the display unit 205, the recording unit 206, and the operating unit 207to supply targets.

As described above, it is possible to prevent the reflection of theincident light by using the above-described solid-state imaging device 1as the solid-state imaging device 202. Therefore, it is possible toimprove the quality of the taken image also in the imaging device 200such as the video camera and the digital still camera, and further acamera module for a mobile device such as a cellular phone.

Meanwhile, the present technology may also have the followingconfigurations.

(1) A solid-state imaging device including:

a semiconductor substrate on which a photoelectric converting unit isformed for each of a plurality of pixels; and

an antireflection structure being the structure provided on a lightincident surface side from which light is incident on the semiconductorsubstrate in which a plurality of types of projections of differentheights is formed.

(2) The solid-state imaging device according to (1) described above,

wherein the antireflection structure is formed by performing processingof digging a light incident surface of the semiconductor substrate in aplurality of stages with different processing conditions.

(3) The solid-state imaging device according to (1) or (2) describedabove,

wherein the antireflection structure is the structure in which a secondprojection lower than a first projection is formed between firstprojections of predetermined height.

(4) The solid-state imaging device according to (3) described above,

wherein the antireflection structure is formed by

forming a mask of a pattern corresponding to a site in which the firstprojection is provided on the light incident surface of thesemiconductor substrate,

performing processing of digging the light incident surface of thesemiconductor substrate with a first processing condition, and

performing processing of further digging the light incident surface witha second processing condition different from the first processingcondition to leave the second projection.

(5) A method of manufacturing including a step of:

forming an antireflection structure being the structure provided on alight incident surface side from which light is incident on asemiconductor substrate on which a photoelectric converting unit isformed for each of a plurality of pixels in which a plurality of typesof projections of different heights is formed by performing processingof digging a light incident surface of the semiconductor substrate in aplurality of stages with different processing conditions.

(6) An electronic device including:

a solid-state imaging device including

a semiconductor substrate on which a photoelectric converting unit isformed for each of a plurality of pixels; and

an antireflection structure being the structure provided on a lightincident surface side from which light is incident on the semiconductorsubstrate in which a plurality of types of projections of differentheights is formed.

Meanwhile, this embodiment is not limited to the above-describedembodiment and may be variously change without departing from the scopeof the present disclosure.

REFERENCE SIGNS LIST

-   1 Solid-state imaging device-   2 Pixel-   3 Pixel array unit-   12 Semiconductor substrate-   21 Semiconductor substrate-   22 Antireflection film-   23 Flattening film-   24 Color filter film-   25 On-chip lens layer-   31 Photoelectric converting unit-   32 Hafnium oxide film-   33 Aluminum oxide film-   34 Silicon oxide film-   35 Light-shielding film-   36 Filter-   37 On-chip lens-   41 Antireflection structure-   42 to 44 Projection-   51 Hard mask layer-   52 Resist-   200 Imaging device-   202 Solid-state imaging device

The invention claimed is:
 1. A light detecting device, comprising: aplurality of pixels arranged in columns and rows, wherein each pixelincludes: a photoelectric conversion region disposed in a semiconductorsubstrate; and a moth-eye structure on a surface of a light incidentside of the semiconductor substrate and over the photoelectricconversion region, wherein the moth-eye structure includes: a firstconvex portion disposed over the photoelectric conversion region; asecond convex portion disposed over the photoelectric conversion region;and a third convex portion disposed over the photoelectric conversionregion, wherein the first convex portion, the second convex portion, andthe third convex portion have different heights respectively in across-sectional view; and a light shielding film disposed betweenadjacent pixels in the cross-sectional view.
 2. The light detectingdevice of claim 1, wherein: the first convex portion is adjacent to thesecond convex portion, and a height of the first convex portion islarger than a height of the second convex portion in the cross-sectionalview.
 3. The light detecting device of claim 1, wherein: the secondconvex portion is adjacent to the third convex portion, and a height ofthe second convex portion is larger than a height of the third convexportion in the cross-sectional view.
 4. The light detecting device ofclaim 1, wherein the second convex portion is disposed between the firstconvex portion and the third convex portion in the cross-sectional view.5. The light detecting device of claim 1, further comprising an oxidefilm including aluminum, the oxide film being disposed on the moth-eyestructure.
 6. The light detecting device of claim 1, further comprisinga flat portion disposed between the first convex portion and the secondconvex portion in the cross-sectional view.
 7. The light detectingdevice of claim 1, wherein the light shielding film includes tungsten.8. An electronic device, comprising: a plurality of pixels arranged incolumns and rows, wherein each pixel includes: a photoelectricconversion region disposed in a semiconductor substrate; and a moth-eyestructure on a surface of a light incident side of the semiconductorsubstrate and over the photoelectric conversion region, wherein themoth-eye structure includes: a first convex portion disposed over thephotoelectric conversion region; a second convex portion disposed overthe photoelectric conversion region; and a third convex portion disposedover the photoelectric conversion region, wherein the first convexportion, the second convex portion, and the third convex portion havedifferent heights respectively in a cross-sectional view; and a lightshielding film disposed between adjacent pixels in the cross-sectionalview.
 9. The electronic device of claim 8, wherein: the first convexportion is adjacent to the second convex portion, and a height of thefirst convex portion is larger than a height of the second convexportion in the cross-sectional view.
 10. The electronic device of claim8, wherein: the second convex portion is adjacent to the third convexportion, and a height of the second convex portion is larger than aheight of the third convex portion in the cross-sectional view.
 11. Theelectronic device of claim 8, wherein the second convex portion isdisposed between the first convex portion and the third convex portionin the cross-sectional view.
 12. A method, comprising: forming aplurality of pixels arranged in columns and rows, wherein each pixelincludes: a photoelectric conversion region disposed in a semiconductorsubstrate; and a moth-eye structure on a surface of a light incidentside of the semiconductor substrate and over the photoelectricconversion region, wherein the moth-eye structure includes: a firstconvex portion disposed over the photoelectric conversion region; asecond convex portion disposed over the photoelectric conversion region;and a third convex portion disposed over the photoelectric conversionregion, wherein the first convex portion, the second convex portion, andthe third convex portion have different heights respectively in across-sectional view; and disposing a light shielding film betweenadjacent pixels in the cross-sectional view.
 13. The method of claim 12,wherein: the first convex portion is adjacent to the second convexportion, and a height of the first convex portion is larger than aheight of the second convex portion in the cross-sectional view.
 14. Themethod of claim 12, wherein: the second convex portion is adjacent tothe third convex portion, and a height of the second convex portion islarger than a height of the third convex portion in the cross-sectionalview.
 15. The method of claim 12, wherein the second convex portion isdisposed between the first convex portion and the third convex portionin the cross-sectional view.